Duplicating thumbnail images in 'Gallery' backend

Hi,

My client is having issues uploading images via the 'Zip Upload' button.

I have managed to replicate the issue, and the process is:
1. Upload folder named '1.zip'
2. 'Gallery' will successfully upload those images
3. Now, we upload folder named '2.zip'.
4. 'Gallery' successfully uploads those images. BUT, the images from '1.zip' will have a duplicate thumbnail.

Further notes:
- Strangely, the original image doesn't exist anymore as it has been deleted, but the original thumbnail image still exists (cached??) in the backend.
- The new, duplicated thumbnail has been given a generated name (eg.1234.jpg), unlike the original thumbnail which has adopted the name of the file as it was on the computer (eg. Boat_Image22.jpg).
- I have manually changed the 'assets/components/gallery/connector.php' file to '644' to fix an earlier problem. Is this the issue? If it is, what should it be?

My system info:
- MODx Revo 2.1.3pl
- Gallery 1.4.0

My colleague found the solution to the issue here:

https://github.com/splittingred/Gallery/issues/119

He did the changes and now it works perfectly!

Does anyone know if there is a solution for single file uploads as I'm having the same trouble and have duplicate thumbnails in the backend?